st: Demeaning TFP

Dear All,
I am trying to assess productivity spillovers from foreign to domestic
firms and am using levpet as my productivity estimation technique.
After I run levpet (both on pooled sample and then industry by
industry) I get some gigantic values for lnTFP.
My sample for running levpet includes both domestic and foreign firms,
i.e. I am not running levpet for domestic firms only.
The summary stats for lnTFP are as follows:
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
lnTFP_pooled | 21923 -1247.003 106482.5 -1.43e+07 17.18935
lnTFP_industry | 18710 -5587274 3.56e+08 -4.57e+10 24.17001
Now I would like to demean TFP but since I have so many really high
negative values, would demeaning lnTFP by country and industry just
make it worse?
Also, I am afraid to restrict the sample to a certain level of lnTFP,
for example as far as - 100.
Preferably I would just restrict the sample to exclude outliers but I
have about 3000 firms which have lnTFP less than -50 in a total sample
of 21923.
Also, if I go ahead and use these lnTFP values in my regression, by
elasticity magnitudes turn up to be 4 digits long. Yikes.
I have tried data transformations and so on but am at a loss. Any
thoughts would be greatly appreciated.
Thanks.
SAM
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